Muscle Contraction

Question: A patient is admitted for electroconvulsive treatment (ECT). The physician orders the neuromuscular blocking agent metocurine iodide (metubine) to reduce trauma by relaxing skeletal muscles. Explain the process of muscle contraction and how a neuromuscular blocking agent, such as metubine, would interfere with muscle contraction. Aaron arrived at the hospital with the following symptoms: drooping eyelids; fatigue and weakness of his muscles; and difficulty talking, breathing and swallowing. What is his diagnosis? Explain.

Answer: There are three different types of muscles in the body which are skeletal, cardiac and smooth. Skeletal muscle is voluntarily controlled and striated, it covers the skeleton. Cardiac muscle surrounds the heart; it is striated and involuntarily controlled. And smooth muscle is found on the walls of hollow visceral organs; it is non-striated and is involuntarily controlled. These muscles perform four important functions for the body which include: producing movement, maintain posture, stabilizing joints and generating heat. What sets muscles apart from all other tissue types is its ability to contract. Contractibility is being able to shorten forcibly when adequately stimulated (Marieb et al., 2007, p.280).

The process of muscle contraction begins when the action potential travels along the sarcolemma and down the T tubules. Upon reaching the T tubules the action potential causes the terminal cisternae of the sarcoplasmic reticulum (SR) to release calcium into the sarcoplasm, where it becomes available to the myofilaments. Then some of this calcium that has been released binds to troponin, which changes shape and removes the blocking action of tropomyosin. Once enough calcium is received the myosin heads attach and pull the thin filaments toward the center of the sarcomere. At this point the muscle cell is considered to be in the active state. The short-lived calcium signal ends, usually within 30 milliseconds after the